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Tue, 20 Jan 2026 06:57:12 -0800 From: Sumit Gupta To: , , , , , , , , , , , , , , , , , , CC: , , , , , , , , Subject: [PATCH v6 4/9] ACPI: CPPC: Add cppc_get_perf() API to read performance controls Date: Tue, 20 Jan 2026 20:26:18 +0530 Message-ID: <20260120145623.2959636-5-sumitg@nvidia.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260120145623.2959636-1-sumitg@nvidia.com> References: <20260120145623.2959636-1-sumitg@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: quoted-printable X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF00000149:EE_|LV2PR12MB5920:EE_ X-MS-Office365-Filtering-Correlation-Id: da2754a1-3adc-48c6-62ba-08de58343cf3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|1800799024|36860700013|921020; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jan 2026 14:57:31.5638 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: da2754a1-3adc-48c6-62ba-08de58343cf3 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF00000149.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV2PR12MB5920 Content-Type: text/plain; charset="utf-8" Add cppc_get_perf() function to read values of performance control registers including desired_perf, min_perf, max_perf, energy_perf, and auto_sel. This provides a read interface to complement the existing cppc_set_perf() write interface for performance control registers. Note that auto_sel is read by cppc_get_perf() but not written by cppc_set_perf() to avoid unintended mode changes during performance updates. It can be updated with existing dedicated cppc_set_auto_sel() API. Use cppc_get_perf() in cppc_cpufreq_get_cpu_data() to initialize perf_ctrls with current hardware register values during cpufreq policy initialization. Signed-off-by: Sumit Gupta --- drivers/acpi/cppc_acpi.c | 80 ++++++++++++++++++++++++++++++++++ drivers/cpufreq/cppc_cpufreq.c | 6 +++ include/acpi/cppc_acpi.h | 5 +++ 3 files changed, 91 insertions(+) diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index a09bdabaa804..de35aeb07833 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -1739,6 +1739,86 @@ int cppc_set_enable(int cpu, bool enable) } EXPORT_SYMBOL_GPL(cppc_set_enable); =20 +/** + * cppc_get_perf - Get a CPU's performance controls. + * @cpu: CPU for which to get performance controls. + * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h + * + * Return: 0 for success with perf_ctrls, -ERRNO otherwise. + */ +int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) +{ + struct cpc_desc *cpc_desc =3D per_cpu(cpc_desc_ptr, cpu); + struct cpc_register_resource *desired_perf_reg, + *min_perf_reg, *max_perf_reg, + *energy_perf_reg, *auto_sel_reg; + u64 desired_perf =3D 0, min =3D 0, max =3D 0, energy_perf =3D 0, auto_sel= =3D 0; + int pcc_ss_id =3D per_cpu(cpu_pcc_subspace_idx, cpu); + struct cppc_pcc_data *pcc_ss_data =3D NULL; + int ret =3D 0, regs_in_pcc =3D 0; + + if (!cpc_desc) { + pr_debug("No CPC descriptor for CPU:%d\n", cpu); + return -ENODEV; + } + + if (!perf_ctrls) { + pr_debug("Invalid perf_ctrls pointer\n"); + return -EINVAL; + } + + desired_perf_reg =3D &cpc_desc->cpc_regs[DESIRED_PERF]; + min_perf_reg =3D &cpc_desc->cpc_regs[MIN_PERF]; + max_perf_reg =3D &cpc_desc->cpc_regs[MAX_PERF]; + energy_perf_reg =3D &cpc_desc->cpc_regs[ENERGY_PERF]; + auto_sel_reg =3D &cpc_desc->cpc_regs[AUTO_SEL_ENABLE]; + + /* Are any of the regs PCC ?*/ + if (CPC_IN_PCC(desired_perf_reg) || CPC_IN_PCC(min_perf_reg) || + CPC_IN_PCC(max_perf_reg) || CPC_IN_PCC(energy_perf_reg) || + CPC_IN_PCC(auto_sel_reg)) { + if (pcc_ss_id < 0) { + pr_debug("Invalid pcc_ss_id for CPU:%d\n", cpu); + return -ENODEV; + } + pcc_ss_data =3D pcc_data[pcc_ss_id]; + regs_in_pcc =3D 1; + down_write(&pcc_ss_data->pcc_lock); + /* Ring doorbell once to update PCC subspace */ + if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) { + ret =3D -EIO; + goto out_err; + } + } + + /* Read optional elements if present */ + if (CPC_SUPPORTED(max_perf_reg)) + cpc_read(cpu, max_perf_reg, &max); + perf_ctrls->max_perf =3D max; + + if (CPC_SUPPORTED(min_perf_reg)) + cpc_read(cpu, min_perf_reg, &min); + perf_ctrls->min_perf =3D min; + + if (CPC_SUPPORTED(desired_perf_reg)) + cpc_read(cpu, desired_perf_reg, &desired_perf); + perf_ctrls->desired_perf =3D desired_perf; + + if (CPC_SUPPORTED(energy_perf_reg)) + cpc_read(cpu, energy_perf_reg, &energy_perf); + perf_ctrls->energy_perf =3D energy_perf; + + if (CPC_SUPPORTED(auto_sel_reg)) + cpc_read(cpu, auto_sel_reg, &auto_sel); + perf_ctrls->auto_sel =3D (bool)auto_sel; + +out_err: + if (regs_in_pcc) + up_write(&pcc_ss_data->pcc_lock); + return ret; +} +EXPORT_SYMBOL_GPL(cppc_get_perf); + /** * cppc_set_perf - Set a CPU's performance controls. * @cpu: CPU for which to set performance controls. diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c index c95dcd7719c3..229880c4eedb 100644 --- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -594,6 +594,12 @@ static struct cppc_cpudata *cppc_cpufreq_get_cpu_data(= unsigned int cpu) goto free_mask; } =20 + ret =3D cppc_get_perf(cpu, &cpu_data->perf_ctrls); + if (ret) { + pr_debug("Err reading CPU%d perf ctrls: ret:%d\n", cpu, ret); + goto free_mask; + } + return cpu_data; =20 free_mask: diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h index 4d644f03098e..3fc796c0d902 100644 --- a/include/acpi/cppc_acpi.h +++ b/include/acpi/cppc_acpi.h @@ -151,6 +151,7 @@ extern int cppc_get_desired_perf(int cpunum, u64 *desir= ed_perf); extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf); extern int cppc_get_highest_perf(int cpunum, u64 *highest_perf); extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_c= trs); +extern int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls); extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls); extern int cppc_set_enable(int cpu, bool enable); extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps); @@ -193,6 +194,10 @@ static inline int cppc_get_perf_ctrs(int cpu, struct c= ppc_perf_fb_ctrs *perf_fb_ { return -EOPNOTSUPP; } +static inline int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrl= s) +{ + return -EOPNOTSUPP; +} static inline int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrl= s) { return -EOPNOTSUPP; --=20 2.34.1